Two-dimensional electrophoresis techniques were refined to study complex cell lysates. By comparison of isogenic strains of E. coli containing mutations in each of the enzymes of the galactose operon, it has been possible to locate the position of each of these enzymes in the two-dimensional electrophoretograms. The position of the kinase enzyme has been corroborated by electrophoresis of double antibody precipitates of the enzyme. Knowledge of the location of these enzymes will facilitate studies of gene expression of lambda transducing virus, carrying the galactose operon. A number of host proteins have been found to be activated by induction of lambda virus, when it is integrated in the host chromosome. These two-dimensional electrophoresis techniques have been used to screen for biochemical abnormalities in human genetic diseases. This effort has been augmented by the development of computer techniques to analyze the complex patterns obtained from body fluids and cell lysates. An alkaline polypeptide, of apparent molecular weight 15,000 daltons, has been observed in the urine of patients with familial Alzheimer's disease, a similar polypeptide has not yet been found in controls. A highly sensitive protein stain has been developed which is 100-times more sensitive than the previously used Commassie Blue stain.